This invention relates to a wire connecting structure and a wire connecting method, in which a plurality of wires are jointly connected to a terminal by rotary swaging or the like.
FIGS. 7 and 8 show one form of wire connecting structure and method (see JP-49-485U)
In this connecting structure and method, conductor portions (wire conductor portions) 33 of two wires 32 and 32 are pressed (clamped) to be connected together, using a joint terminal 31.
The joint terminal 31 is formed by blanking a piece from a single electrically-conductive metal sheet and then by curving it into a curl shape, and a pair of right and left circumferentially-extending notches 34 are formed in a longitudinally-intermediate portion thereof to thereby form a pair of right and left curved press-fastening piece portions (press-clamping piece portions) 35 and 35 at each of front and rear portions of the terminal. As another form of joint terminal 31, there may be used one including a base plate portion (not shown) of a generally flat plate-like shape, and two pairs of press-fastening piece portions (not shown), each pair of press-fastening piece portions extending upwardly from opposite (right and left) side edges of the base plate portion, respectively.
As shown in FIG. 7, the two front and rear wires 32 and 32 are inserted and set in the joint terminal 31, and for example, by the use of a terminal clamping machine (not shown), each press-clamping piece portion 35 is pressed between an upper crimper (upper die) and a lower anvil (lower die) to be formed into a curl shape, thereby connecting the conductor portions 33 and 33 of the two wires 32 and 32 together.
Usually, the wire 32 is inserted into the joint terminal 31 through an opening between the right and left press-fastening piece portions 35 and 35. An insulating sheath 36 of each wire 32 is fixed, for example, by a clip, provided on the wire clamping machine, thereby holding each wire 32 against displacement in the forward and rearward directions, and in this condition the above press-fastening operation is effected. The pair of front press-fastening piece portions 35 and the pair of rear press-fastening piece portions 35 are press-deformed respectively by the separate crimper (upper die)-anvil (lower die) structures (Even if the two are integral with each other, they are spaced from each other in the longitudinal direction of the terminal), or after the pair of front press-clamping piece portions 35 are press-deformed, the pair of rear press-clamping piece portions 35 are press-deformed, so that bell mouths (bulge portions) 37 are formed respectively at the front and rear ends of each press-fastening piece portion 35 as shown in FIG. 8.
The number of the wires 32 is not limited to two, but may be three or more, and there can be provided a joint or branch connection in which for example, one wire extends forwardly from the joint terminal 31 while two wires extend rearwardly from the joint terminal. The branch connection is a kind of joint connection, and is one form of connection by which, for example, a power source is distributed from one power source wire to a plurality of branch wires.
Using the type of joint terminal which is provided not with two (front and rear) pairs of press-fastening piece portions (press-clamping piece portions) but with a pair of right and left press-fastening piece portions, two wires 32 and 32 can be set in the terminal not from front and rear directions (different directions) but from the same direction, and can be arranged in parallel relation. In this case, also, three or more wires 32 can be press-fastened at the same time.
In the above conventional wire connecting structure and method, however, the conductor portions 33 and 33 of the two wires 32 and 32, pressed to be connected together by the joint terminal 31, are liable to be separated right and left from each other as shown in FIG. 9, and in this case a gap 38 is formed between the two conductor portions 33 and 33, and this often deteriorated the contact ability. Particularly when the pair of right and left press-clamping piece portions or each pair of press-clamping piece portions are press-deformed into a curl shape by the crimper (upper die) and anvil (lower die) of the press-clamping machine as shown in FIG. 9, press-fastening forces, exerted in the upward and downward directions (directions of arrows H), tend to be large while press-fastening forces, exerted in the right and left directions (directions of arrow I), tend to be small, and therefore there has been encountered a problem that gaps are liable to develop between the right and left conductor portions 33 and 33 and between the outer surface of each of the right and left conductor portions 33 and 33 and the inner surface of a right (left) portion of each press-clamping piece portion 35.
Depending on the pressing conditions and so on of the clamping machine, gaps developed between element wires of the conductor portion 33 (One conductor portion is formed by a plurality of element wires), and also gaps developed between the inner surface of the joint terminal 31 and the element wires, which deteriorated the contacting ability. Particularly when three or more wires 32 were used, or thick wires 32 for a power source or the like were used, so that the total number of element wires increased, there was encountered a problem that such gaps were liable to develop. When gaps thus developed between the conductor portions 33 and between the element wires, there was encountered a problem that not only the electrical contact performance was deteriorated, but also the connecting portion, including the joint terminal 31, and its neighboring portion were heated to be adversely affected.
When an aluminum material was used for the joint terminal 31 and/or the conductor portion 33 of each wire 32, an oxide film was liable to deposit on the inner surface of the joint terminal 31 and/or the surface of each conductor portion 33 with the lapse of time, and particularly when gaps existed between the joint terminal 31 and the conductor portion 33 and between the element wires of the conductor portion 33, an oxide film was liable to deposit on such gap portions, which invited a problem that the conducting resistance increased, so that the conducting ability was deteriorated.
On the other hand, there are known a structure and a method in which instead of the joint terminal of the above form, there is used a joint terminal (particularly for use with a large current), having a tubular portion (not shown), and conductor portions 33 of wires 32 are inserted into the tubular portion, and the tubular portion is compressively pressed at four to six points on its outer peripheral surface, and is connected to the conductor portions 33. In this case, there was been encountered a problem that stresses concentrated on the four to six pressed portions of the tubular portion, and the contact of the remaining portions with the conductor portion 33, as well as the intimate contact within the conductor portion 33, were liable to be deteriorated.
With the problems of the above forms in view, it is an object of this invention to provide a wire connecting structure and a wire connecting method, in which in the joint connection of wires, including a branch connection, any gap will not develop between a terminal and each conductor portion, between the conductor portions and between elements wires, forming each conductor portion, thereby enhancing the reliability of the electrical connection, and besides even when there are used those terminal and conductor portions which are made of an aluminum material, the good electrical connection can be obtained.
In order to achieve the above object, the present invention provides a wire connecting structure characterized in that conductor portions of a total of two or more wires are compressively pressed uniformly over an entire periphery within one or a plurality of tubular portions of a terminal, and are connected thereto.
Effectively, the terminal has a pair of tubular portions formed respectively at opposite sides thereof, and the conductor portions of one or more wires are compressively pressed uniformly over the entire periphery within each of the tubular portions, and are connected thereto.
Effectively, in the wire connecting structure, the terminal has one tubular portion, and the conductor portions of the plurality of wires are compressively pressed uniformly over the entire periphery within the tubular portion in such a manner that the conductor portions are combined together.
In order to achieve the above object, the invention also provides a wire connecting method characterized in that conductor portions of a total of two or more wires are inserted into one or a plurality of tubular portions of a terminal, and the tubular portion is compressively pressed uniformly over an entire periphery thereof.
In the wire connecting method, effectively, the compressive pressing of the tubular portion is effected by a rotary swaging machine.